Hydraulic jack base structure

ABSTRACT

An improved hydraulic jack structure which avoids the necessity of a complex base casting or a multipart base assembly by substituting a simple baseplate formed from initially flat plate material by simple and inexpensive press and drilling operations. The baseplate particularly includes a tongue formed unitarily from the plate and having a free end extending upwardly at a small angle, to receive pressure release and other valve components.

rte ma5 Patent 1 [111 3,71,619 Simon Mar. 18, 1975 [54] HYDRAULIC JACK BASE STRUCTURE 2,799,993 7/1957 Stovern et al 60/482 Inventor: Ernest M. Simon, Golden y, 2,828,611 4/1958 Johansson et a1 60/481 M' n. m Primary Examiner-Othell M. Simpson Asslgneei Manufacturing Attorney, Agent, or Firm-Merchant, Gould, Smith &

Minneapolis, Minn. Ed|| [22] Filed: Mar. 18, 1974 1211 Appl. No; 451,908 [571 ABSTRACT An improved hydraulic jack structure which avoids the necessity of a complex base casting or a multipart [52] US. Cl 25 1/93 1R, 60/458, 6606747821, 7 base assembly y Substituting a Simple baseplate [51] Int Cl B6 3/24 formed from initially flat plate material by simple and [58] Fieid H 93 inexpensive press and drilling operations. The base- 458 481 6 6 plate particularly includes a tongue formed unitarily from the plate and having a free end extending up [56] References Cited wardly at a small angle, to receive pressure release UNITED STATES PATENTS Kemerer 254/93 H and other valve components.

2 Claims, 6 Drawing Figures PAIENTED MAR] 8:975 3. 87 1L 1 9 20 FIG. 2

I I I "f H 27 i M 34 FIG. I I {II 26 I lib/11111 711 75 Farr, 7 2M? p ll HYDRAULIC JACK BASE STRUCTURE BACKGROUND OF THE INVENTION This invention relates to the field of hydraulic jacks. It has been customary in constructing such jacks to use a casting of relatively complex configuration as the baseplate in which other elements are mounted, or to build up such a baseplate from a number of individual parts. Castings of the sort referred to are expensive and difficult to procure with a reasonable lead time, and use of plural parts increases the expense both of manufacture and assembling the baseplate.

SUMMARY OF THE INVENTION It is a principle object of this invention to provide an improved hydraulic jack in which complicated base castings or multipart base structure are avoided, and in which simple plate, bar, and tube stock is sufficient formost elements, and pressing, drilling, and welding operations are those relied on in manufacture.

A particular object of the invention is to provide a baseplate for a hydraulic jack which is fabricated unitarily from metal plate, using only pressing and drilling operations, to provide a tongue integral with the rest of the plate and extending upwardly therefrom at a small angle, to accommodate and in part comprise a combined valve means for the jack.

Various other objects, advantages, and features of novelty which characterize my invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and objects attained by its use, reference should be had to the drawing which forms a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawing FIG. 1 is a perspective view of a hydraulic jack according to my invention;

FIG. 2 is a longitudinal section taken along the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a fragmentary plan view, partly in section along the line 4-4 of FIG. 1;

FIG. 5 is a fragmentary end elevation from the line 5-5 of FIG. 2; and

FIG. 6 is a fragmentary bottom view of the baseplate showing a detail of construction.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawing, my hydraulic jack l comprises a casing 11 tightly secured at its bottom end, as by welding, to a rectangular baseplate 12 of relative thick sheet metal. Casing 11 is closed at its upper end by a cap ring 13 which may be a press fit therein. Contained within the casing 11 is a pressure cylinder 14, also tightly secured at its bottom end to baseplate 12, and received in ring 13.

The volume between members 11 and 14 functions as a reservoir 15 for hydraulic fluid 16, and a filler plug 17 is provided in casing 11 through which the fluid may be introduced.

A plunger -20 having a bore 21 slides in cylinder 14 and comprises a tubular piston 22 closed at its bottom end by a header 23 of slightly larger diameter, pressed tightly therein and grooved externally at 24 to receive a hydraulic packing 25 of suitable type for the pressure to be used. An internal groove 26 is formed in cap ring 13 to receive packing 27, but the pressure requirements here are not so demanding as at 25. It will be apparent that when fluid is forced from reservoir 15 into the pressure cylinder below header 23, as will presently be explained, the plunger will be forced upwardly, piston 20 sliding in packing 27, and packing 27 sliding in cylinder 14. For convenience members 11, 14, and 20 may be circularcylinders of appropriate wall thickness, in which case headers 23 will also be circular in cross section. A vent 28 provides a passage for air between the upper portion of reservoir 15 and the upper portion of the space within cylinder 14 and above header 23.

The stroke or lift of jack 10 is determined by the maximum distance between ring 13 and a shoulder 29 on header 23. To maintain as much of the lift available as possible, and to minimize the effort required of the jack user in assembling blocking materials, a length adjustment for plunger 20 is provided which includes as additional elements a helical spring 30 and a plug 31. Bore 21 of piston 22 is of circular :section, and receives the body 32 of plug 31 for rotation therein. At its upper end plug 31 is provided with an enlarged head 33, which engages the top of piston 22 when the plug is completely inserted in the piston. For minimum initial height of the jack, the length of the plug body may then be any distance less than that from the outer end of piston 22 to the top of header 23, and for maximum available height adjustment the lengths should be equal.

Spring 30 may conveniently be wound from wire of circular cross section. It is preferably a right-handed helix, the pitch diameter of which is substantially the same as the diameter of bore 21 and that of plug body 32. The pitch of the helix is preferably somewhat greater than the diameter of the wire, to give an open helix with space between the turns. In length the spring may be considerably less than bore 21. Spring 30 is tightly secured within bore 21 near the mouth thereof in a suitable manner. I prefer to do this by forming an internal helical groove 35 in piston 22 extending from the mouth thereof. The form of the groove, for circular wire, is substantially a semi-circle of the diameter of the wire: its handedness and pitch must agree with that of the spring. The root diameter of the spiral groove is however slightly less than the outside diameter of the spring in its free state; then when the spring is screwed into the groove and released its inherent resilience maintains it in a friction contact with the groove sufficient to permit any relative motion therebetween.

To cooperate with the spring 30 the body of plug 31 is externally grooved for substantially its full length in a helix of the same pitch and handedness, the groove being again substantially a semi-cross section of the spring wire, that is, a semi-circle. In this case, however, the root diameter of the groove is slightly less than the inside diameter of the spring as installed in the piston, so that the plug interfits with the spring in screwthreaded relation, while the openness of the helix as sures bearing contact between the plug body and the piston wall between the helix turns to give a mechanically firm relation without lateral play. For ease in manufacture the body of the plug near head 33 may have a short groove 34: the greater diameter of the head not only provides a shoulder for contacting piston 22, but also facilitates the gripping of the plug to rotate it manually until the desired initial plunger length has been attained.

The method of transferring fluid from reservoir into cylinder will now be described. A pump of conventional nature is shown to comprise a body 41 secured at its bottom to baseplate 12 in any fluid-tight fashion, and a plunger 42 reciprocable vertically therein and having a portion extending upwardly through a suitable packing 43. Piston 42 is pivotally connected at 44 to a socket 45, the latter in turn being connected to baseplate 12 by a link 46 pivoted at 47 and 50. A tubular handle 51 is removably received in socket and the socket end of the handle is formed hexagonally at 52 for a purpose to be described below. As handle 51 is reciprocated up and down, piston 42 moves in cylinder 41. A pair of lugs 53 and 54 may be formed on socket 45 to prevent handle 51 from being moved so far as to pull piston 42 too high in cylinder 41.

A tongue is formed unitary with baseplate 12 by hydro-forming or other suitable process, to have an outer free end 61 and to extend at a small angle upwardly from the baseplate. The tongue has a longitudinal bore 62 to comprise portions of a combined valve 63 including a pressure release valve and a pump outlet checkvalve generally indicated by the reference numerals 64 and 65, respectively, the bore having a plurality of interconnecting chambers extending from its free end into the undistorted metal of the baseplate,- and including a first chamber 66, a second chamber 67, and a third chamber 68.

Pressure release valve 64 comprises a ball 70, a seat 71, and means 72 for mechanically and releasably maintaining the ball in sealing contact with the seat, including a member 73 threaded into tongue 60 at its free end and having a hexagonal head 74 which fits the hexagonal end 52 of tubular handle 51, so that the latter may be used as an extension wrench to tighten and loosen member 73. An O-ring 75 prevents leakage of fluid around member 73. Pump outlet checkvalve comprises a seat 76, a ball 77, and a compression spring 78 engaging ball at one end and ball 77 at the other end.

Baseplate 12 also includes a pump inlet checkvalve 80 including a seat 81, a ball 82, and a compression spring 83 backed by a locking screw 84, all contained in a transverse bore 85 in the baseplate sealed by screw 84. Bore 85 communicates with a short vertical bore 86 in the baseplate, positioned to communicate directly with cylinder 41 of pump 40: chamber 68 also communicates directly with bore 86.

A plurality of further vertical bores 90, 91 and 92 are formed in baseplate 12, and are connected by cross bores 93, 94 and 95 with chamber 66, chamber 67, and bore 85, all respectively. Bores 93 and 94 are sealed at their outer ends by steel balls 95 and 96 pressed into the baseplate and crimped there. Bore 91 communicates with the inside of the pressure cylinder below header 23, while bores and 92 communicate with the fluid reservoir.

When it is desired to use my hydraulic jack, baseplate 12 is rested on a secure foundation, with piston 20 in its fully retracted position, and plug 22 is screwed out of the piston by rotating head 33 until contact with the object to be raised is made.

The hexagonal socket end 52 of handle 51 is placed on the hexagonal head 74 of member 73 and rotated until ball 70 is pressed into engagement with seat 71. The the handle is inserted in socket 45 and moved up and down to transfer fluid 16 from reservoir 15 to cylinder 14 under piston 20. Each upstroke of the handle draws fluid from reservoir 15 through bore 92, cross bore and bore 86, ball 82 being displaced against the pressure of spring 83 to permit the flow. At the same time ball 77 is maintained against seat 76 by spring 78. The next downstroke of handle 51 causes piston 42 to force fluid out through bore 86, chambers 68 and 67,

cross bore 94, and bore 91 into the pressure cylindr, ball 77 being displaced against the pressure of spring 78 to permit the flow: at the same time ball 82 is maintained against seat 81 to prevent fluid flow back into the reservoir. This process is continued until the desired amount of lift has been attained.

When it is desired to lower the object, handle 51 is placed in engagement with head 74 and member 73 is rotated to release the force on ball 70, which is moved out of seat 71 by the fluid pressure, allowing fluid to pass through bore 91, cross bore 94, chambers 67 and 66, cross bore 93, and bore 90 to reservoir 15.

Numerous objects and advantages of my invention have been set forth in the foregoing description, together with details of the structure and function of the invention, and the novel features thereof are pointed out in the appended claims. The disclosure, however, is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts, within the principle of the invention, to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

What is claimed is:

1. In a hydraulic jack having a fluid reservoir, a pressure cylinder, a pump cylinder, a pump inlet checkvalve, and combined valve means including a pump outlet checkvalve and pressure release valve:

a baseplate having openings arranged for communication with the pump cylinder, the pressure cylinder, and the fluid reservoir;

first passage means in said base, including the inlet checkvalve, extending between the fluid reservoir opening and the pump cylinder opening;

second passage means in said base, including the outlet checkvalve, extending between the pump cylinder opening and the pressure cylinder opening;

third passage means in said base, including the pressure release valve, extending between the pressure cylinder opening and the fluid reservoir opening;

said base comprising a flat plate having a tongue hydro-formed therefrom so as to extend at one end at an acute angle above said plate and so as to be metallurgically unitary with said plate at its other end;

said second and third passage means extending continuously from said plate into said tongue transversely thereof near said other end thereof;

and said combined valve means extending longitudinally in said tongue from said one end thereof.

2. Apparatus according to claim 1 in which the combined valve means comprises a plurality of interconnecting chambers extending from said one end of the tongue and including in sequence a first chamber comprised in the third 6 from the second chamber to the first chamber and comprising the pressure release valve;

and manually actual means in said first chamber and extending therefrom at one end of the tongue, for

opening the normally closed valve means. 

1. In a hydraulic jack having a fluid reservoir, a pressure cylinder, a pump cylinder, a pump inlet checkvalve, and combined valve means including a pump outlet checkvalve and pressure release valve: a baseplate having openings arranged for communication with the pump cylinder, the pressure cylinder, and the fluid reservoir; first passage means in said base, including the inlet checkvalve, extending between the fluid reservoir opening and the pump cylinder opening; second passage means in said base, including the outlet checkvalve, extending between the pump cylinder opening and the pressure cylinder opening; third passage means in said base, including the pressure release valve, extending between the pressure cylinder opening and the fluid reservoir opening; said base comprising a flat plate having a tongue hydro-formed therefrom so as to extend at one end at an acute angle above said plate and so as to be metallurgically unitary with said plate at its other end; said second and third passage means extending continuously from said plate into said tongue transversely thereof near said other end thereof; and said combined valve means extending longitudinally in said tongue from said one end thereof.
 2. Apparatus according to claim 1 in which the combined valve means comprises a plurality of interconnecting chambers extending from said one end of the tongue and including in sequence a first chamber comprised in the third passage means, a second chamber comprised in the second and third passage means, and a third chamber comprised in the first passage means; an automatic checkvalve preventing flow of fluid from said second chamber to said third chamber and comprising the pump outlet checkvalve; normally closed valve means preventing flow of fluid from the second chamber to the first chamber and comprising the pressure release valve; and manually actual means in said first chamber and extending therefrom at one end of the tongue, for opening the normally closed valve means. 